Rationale. Diets rich in tomato products and soy are hypothesized to reduce the risk of prostate cancer or perhaps, enhance the efficacy of prostate cancer therapy. Supporting data is derived from epidemiologic investigations, rodent models, and in vitro cell culture studies. Our research team has developed a processed food/nutriceutical combining lycopene-rich tomato juice with soy germ, with the goal of developing a standardized and easily consumed nutriceutical that can be employed in future large-scale, randomized, long-term intervention trials focusing upon prevention or treatment of prostate cancer. Hypothesis. We propose that a daily serving of a novel tomato-soy nutriceutical (OSU-TSJ-001) will cause a dose dependent increase in bioactive components (isoflavones, polyphenols, carotenoids) in the prostate, and alter biomarker patterns suggesting chemopreventive or therapeutic properties for prostate cancer. Experimental Approach. We will conduct a dose escalating phase I pre-prostatectomy clinical trial in 60 men that have clinically localized prostate cancer and have chosen prostatectomy for therapy. The dose escalating study will begin with 15 men consuming usual diets as the control group, with subsequent cohorts of 15 men consuming 5 oz per day, 10 oz per day, and 15 oz per day of the tomato-soy juice (OSU-TSJ-001). Men will consume the tomato-soy nutriceutical for a target of 28 days prior to undergoing prostatectomy. Aim 1. We hypothesize men will be compliant with consumption of the tomato-soy nutriceutical (OSU-TSJ- 001 ) with no dose limiting toxicity. History indicates that efforts to define toxicity and safety profiles are essential. Aim 2. We hypothesize that consumption of the tomato-soy nutriceutical (OSU-TSJ-001) will result in a dose dependent increase in the biodistribution of tomato-soy phytochemicals in blood and prostate tissue. Aim 3. We hypothesize that consumption of the tomato-soy nutriceutical (OSU-TSJ-001) alters blood hormonal patterns and biomarkers of oxidative stress that favor prostate cancer prevention. Aim 4. We will investigate histopathologic and molecular biomarkers associated with prostate carcinogenesis that may serve as surrogate endpoint biomarkers and provide information regarding their ability to be modulated by the tomato-soy nutriceutical (OSU-TSJ-001). Significance. The proposed study represents the first attempt to evaluate a novel "functional food" / neutriceutical containing tomato and soy components in a clinical trial targeting prostate cancer. Our objective is to develop the tomato-soy juice for future large scale randomized trials evaluating prostate cancer prevention or improved cancer therapy (prevent recurrence or improve outcomes of hormonal, biological, or chemical therapy). The phase I / II study provides essential safety and efficacy data along with valuable information regarding absorption and biodistribution of tomato-soy phytochemicals and the characterization of surrogate endpoint biomarkers relevant to mechanisms of action that may be useful in future randomized clinical trails.